Definition of Mitigating Circumstances
To mitigate means to "become less harsh or hostile, to alleviate or mollify." Mitigating circumstances are factors which may partially explain or excuse a defendant's behavior. Mitigating circumstances do not excuse the culpability of the defendant but may allow the jury to view their actions as less egregious and allow the court to reduce the charges or lesson the sentence if the defendant is convicted.
There are a wide variety of factors which can be considered mitigating. For instance, if a crime is committed in a heat of passion, the plaintiff has diminished mental capacity, the crime was an accident, the defendant was abused or the defendant expresses remorse, these all could be considered in the sentencing phase of the trial.